From 3db63d2c2d1d1e78615dd742568c5a2d55291ad1 Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Sat, 1 Nov 2025 19:04:29 +0300 Subject: [PATCH] ext4: check if mount_opts is NUL-terminated in ext4_ioctl_set_tune_sb() params.mount_opts may come as potentially non-NUL-term string. Userspace is expected to pass a NUL-term string. Add an extra check to ensure this holds true. Note that further code utilizes strscpy_pad() so this is just for proper informing the user of incorrect data being provided. Found by Linux Verification Center (linuxtesting.org). Signed-off-by: Fedor Pchelkin Reviewed-by: Baokun Li Reviewed-by: Jan Kara Message-ID: <20251101160430.222297-2-pchelkin@ispras.ru> Signed-off-by: Theodore Ts'o Cc: stable@kernel.org --- fs/ext4/ioctl.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 366a9b615bf08..7ce0fc40aec2f 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -1394,6 +1394,10 @@ static int ext4_ioctl_set_tune_sb(struct file *filp, if (copy_from_user(¶ms, in, sizeof(params))) return -EFAULT; + if (strnlen(params.mount_opts, sizeof(params.mount_opts)) == + sizeof(params.mount_opts)) + return -E2BIG; + if ((params.set_flags & ~TUNE_OPS_SUPPORTED) != 0) return -EOPNOTSUPP; -- 2.47.3